System and method for forming an integrated barrier layer

ABSTRACT

An apparatus and method for forming an integrated barrier layer on a substrate is described. The integrated barrier layer comprises at least a first refractory metal layer and a second refractory metal layer. The integrated barrier layer is formed using a dual-mode deposition process comprising a chemical vapor deposition (CVD) step and a cyclical deposition step. The dual-mode deposition process may be performed in a single process chamber.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/414,271, entitled “System and Method for Forming an IntegratedBarrier Layer”, filed Apr. 15, 2003, which claims the benefit of U.S.Provisional Application No. 60/386,221 filed Apr. 16, 2002, which areherein incorporated by references.

BACKGROUND OF THE DISCLOSURE

1. Field of the Invention

Embodiments of the present invention generally relate to a method ofbarrier layer formation and, more particularly to a method of integratedbarrier layer formation using both cyclical deposition techniques andchemical vapor deposition techniques.

2. Description of the Background Art

In the manufacture of integrated circuits, contact level metallizationschemes are often used to provide low resistance contacts to anunderlying semiconductor material. Typically, contact levelmetallization schemes combine an integrated barrier layer with a contactlevel metal layer.

For example, when a gate electrode of a transistor is fabricated, anintegrated barrier layer (e.g., titanium nitride/tungsten (TiN/W)) isformed between the gate material (e.g., polysilicon) and the contactlevel metal layer (e.g., aluminum (Al) or copper (Cu)) of the gateelectrode. The integrated barrier layer inhibits the diffusion of thealuminum (Al) or copper (Cu) into the polysilicon gate material. Suchaluminum (Al) or copper (Cu) diffusion is undesirable because itpotentially changes the characteristics of the transistor, rendering thetransistor inoperable.

The integrated barrier layer typically comprises two different materiallayers. Each of the material layers is typically formed using a separateprocess chamber. For example, separate deposition chambers may be usedfor depositing the titanium nitride (TiN) layer and the tungsten (W)layer comprising a titanium nitride/tungsten (TiN/W) integrated barrierlayer. The separate deposition chambers may include, for example,physical vapor deposition (PVD) chambers and/or chemical vapordeposition (CVD) chambers. However, the use of separate depositionchambers to form each material layer comprising the integrated barrierlayer is costly.

Additionally, as circuit densities increase, the widths of integratedcircuit features such as, for example, gate electrodes, may decrease tosub-micron dimensions (e. g., less than 0.25 micrometers), whereas thethickness of material layers between such features typically remainssubstantially constant, increasing the aspect ratios therefor. The termaspect ratio as used herein refers to the ratio of the feature heightdivided by the feature width. Many traditional deposition processes havedifficulty filling sub-micron features where the aspect ratio exceeds8:1, and especially where the aspect ratio exceeds 10:1.

FIG. 1 illustrates the possible consequences of material layerdeposition in a high aspect ratio feature 6 formed on a substrate 1. Thehigh aspect ratio feature 6 may be any opening such as a space formedbetween adjacent features 2, a contact, a via, or a trench defined in amaterial layer. As shown in FIG. 1, a material layer 11 that is formedusing conventional deposition techniques (e.g., chemical vapordeposition (CVD) and/or physical vapor deposition (PVD)) tends to bedeposited on the top edges 6T of the feature 6 at a higher rate than atthe bottom 6B or sides 6S thereof creating an overhang. This overhang orexcess deposition of material is sometimes referred to as crowning. Suchexcess material continues to build up on the top edges 6T of the feature6, until the opening is closed off by the deposited material 11, forminga void 4 therein. The presence of voids may result in unreliableintegrated circuit performance.

Therefore, a need exists for a system and method for forming integratedbarrier layer structures.

SUMMARY OF THE INVENTION

An apparatus and method for forming an integrated barrier layer on asubstrate is described. The integrated barrier layer comprises at leasta first refractory metal layer and a second refractory metal layer. Theintegrated barrier layer is formed using a dual-mode deposition processcomprising a chemical vapor deposition (CVD) step and a cyclicaldeposition step. The dual-mode deposition process may be performed in asingle process chamber.

In one embodiment, the apparatus includes a process chamber having a gasdistribution plate therein. The gas distribution plate is configured toinclude two distribution zones for providing process gases to thechamber for both the chemical vapor deposition (CVD) process and thecyclical deposition process. A first distribution zone comprises acenter opening through which process gases for the cyclical depositionprocess are provided to the process chamber. A second distribution zonecomprises a plurality of openings radially dispersed around the centeropening. The first distribution zone and the second distribution zoneare isolated from one another to inhibit mixing of the process gases.

In operation, a substrate is provided to the process chamber. A firstrefractory metal layer may be formed on the substrate using a chemicalvapor deposition (CVD) process. Thereafter, a second refractory metallayer may be formed on the first refractory metal layer using a cyclicaldeposition process. Each of the first and second refractory metal layersmay comprise a different refractory metal. For example, the integratedbarrier layer may comprise a titanium nitride (TiN) layer formed using achemical vapor deposition (CVD) process and a tungsten (W) layer formedon the titanium nitride (TiN) layer using a cyclical deposition process.

The integrated barrier layer is compatible with integrated circuitfabrication processes. In one integrated circuit fabrication process,the integrated barrier layer may be used in a copper (Cu) interconnectstructure. For a copper (Cu) interconnect fabrication process, apreferred process sequence includes providing a substrate having aninterconnect pattern defined in a dielectric material layer. Anintegrated barrier layer comprising a first refractory metal layerformed with a chemical vapor deposition (CVD) process and a secondrefractory metal layer formed with a cyclical deposition process isdeposited on the interconnect pattern defined in the dielectric materialusing a single process chamber. Thereafter, the interconnect structureis completed by filling the interconnect pattern defined in thedielectric material with copper (Cu).

In another integrated circuit fabrication process, the integratedbarrier layer may be used as a diffusion barrier for gate electrodes.For a gate electrode fabrication process, a preferred process sequenceincludes providing a substrate having gate regions formed on the surfacethereof. The gate regions are surrounded by a dielectric material. Anintegrated barrier layer comprising a first refractory metal layerformed with a chemical vapor deposition (CVD) process and a secondrefractory metal layer formed with a cyclical deposition process isdeposited on the gate regions using a single process chamber.Thereafter, the gate electrodes are completed by depositing a gate metallayer on the integrated barrier layer.

The integrated barrier layer may also be used as a diffusion barrier forone or more electrodes of three-dimensional capacitor structures such asfor example, trench capacitors and crown capacitors. For a trenchcapacitor structure, a preferred process sequence includes providing asubstrate having trenches defined therein. The trenches include a firstelectrode and a dielectric material conformably formed along thesidewalls of the trenches. An integrated barrier layer comprising afirst refractory metal layer formed with a chemical vapor deposition(CVD) process and a second refractory metal layer formed with a cyclicaldeposition process is deposited on the dielectric material in thetrenches using a single process chamber. Thereafter, the trenchcapacitor structure is completed by depositing a second electrode on theintegrated barrier layer.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention are attained and can readily be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of the invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a cross-sectional view of one possible deposition result forhigh aspect ratio features filled using conventional prior artdeposition techniques;

FIGS. 2A-2B depicts a schematic cross-sectional view of a processchamber and a top view of a gas distribution plate that can be used forthe practice of embodiments described herein;

FIG. 3 is a block diagram of a gas delivery system for the gasdistribution plate shown in FIG. 2B;

FIG. 4 illustrates a process sequence for integrated barrier layerformation;

FIG. 5 illustrates a process sequence for material layer formation usingcyclical deposition techniques according to one embodiment describedherein;

FIG. 6 illustrates a process sequence for material layer formation usingcyclical deposition techniques according to an alternate embodimentdescribed herein;

FIGS. 7A-7C illustrate schematic cross-sectional views of a substrate atdifferent stages of an interconnect fabrication sequence;

FIGS. 8A-8C illustrate schematic cross-sectional views of a substrate atdifferent stages of a gate electrode fabrication sequence;

FIGS. 9A-9D illustrate schematic cross-sectional views of a substrate atdifferent stages of a trench capacitor fabrication sequence; and

FIGS. 10A-10B depict cross-sectional views of a substrate at differentstages of a crown capacitor fabrication sequence.

DETAILED DESCRIPTION

FIG. 2A depicts a schematic cross-sectional view of a process chamber 10that can be used to perform deposition processes in accordance withembodiments described herein. The process chamber 10 generally houses awafer support pedestal 48, which is used to support a substrate (notshown). The wafer support pedestal 48 is movable in a vertical directioninside the process chamber 10 using a displacement mechanism 48 a.

Depending on the specific deposition process, the substrate can beheated to some desired temperature prior to or during deposition. Forexample, the wafer support pedestal 48 may be heated using an embeddedheater element 52 a. The wafer support pedestal 48 may be resistivelyheated by applying an electric current from an AC power supply 52 to theheater element 52 a. The substrate (not shown) is, in turn, heated bythe pedestal 48. Alternatively, the wafer support pedestal 48 may beheated using radiant heaters such as, for example, lamps (not shown).

A temperature sensor 50 a, such as a thermocouple, is also embedded inthe wafer support pedestal 48 to monitor the temperature of the pedestal48 in a conventional manner. The measured temperature is used in afeedback loop to control the AC power supply 52 for the heating element52 a, such that the substrate temperature can be maintained orcontrolled at a desired temperature which is suitable for the particularprocess application.

A vacuum pump 18 is used to evacuate the process chamber 10 and tomaintain the pressure inside the process chamber 10. A gas manifold 34,through which process gases are introduced into the process chamber 10,is located above the wafer support pedestal 48. The gas manifold 34 iscoupled to a gas panel 51, which controls and supplies various processgases to the process chamber 10.

Proper control and regulation of the gas flows to the gas manifold 34are performed by mass flow controllers (not shown) and a microprocessorcontroller 70. Additionally, the gas manifold 34 may optionally beheated to prevent condensation of the reactive gases within themanifold.

The gas manifold 34 includes a gas distribution plate 35. Referring toFIG. 2B, the gas distribution plate 35 is configured to include two gasdistribution zones 42, 45 for providing process gases to the processchamber for either a chemical vapor deposition (CVD) process or acyclical deposition process. A first gas distribution zone 45 comprisesa center opening 36 through which process gases for the cyclicaldeposition process are provided to the process chamber. A second gasdistribution zone 42 comprises a plurality of openings 37 radiallydispersed around the center opening 36.

The first gas distribution zone 45 and the second gas distribution zone42 are isolated from one another using one or more seals 38, 47 whichinhibit mixing of the process gases provided thereto. The one or moreseals 38, 47 may comprise any suitable material that is non-reactivewith the process gases provided to the process chamber, such as, forexample, an o-ring.

FIG. 3 depicts a gas distribution system 50 that may be used to provideprocess gases to the gas distribution plate 35 (FIG. 2A). The gasdistribution system 50 includes process gas supplies 53, 55, 57, 59,purge gas supplies 85, 86, electronic control valves 60, 61, mass flowcontrollers (MFC) 64, 65, gas splitters 81, 82, a three-position valve75 and a premix chamber 80.

For the cyclical deposition mode, a process gas from supplies 57, 59 isprovided to electronic control valves 60, 61, respectively. A purge gasfrom the purge gas supply 85 may be mixed with the process gases throughgas splitters 81, 82. The electronic control valves 60, 61 as usedherein refer to any control valve capable of providing rapid and precisegas flow to the process chamber 10 with valve open and close cycles ofless than about 1-2 seconds, and more preferably less than about 0.1second. The electronic control valves 60, 61 are coupled to the centeropening 36 in the first gas distribution zone 45, via three-positionvalve 75 and gas line 88.

For the chemical vapor deposition (CVD) mode, process gases from gassupplies 53, 55 are coupled through mass flow controllers (MFC) 64, 65,respectively, to premix chamber 80. A purge gas from purge gas supply 86may also be provided to the premix chamber 80. In the premix chamber 80,the process gases are caused to mix. Generally, these gases arereactants that will react when they are exposed to a heated substrate.The mixed gases are provided from the premix chamber 80 to the pluralityof openings 37 in the second gas distribution zone 42 via gas line 87.

The microprocessor controller 70 may be one of any form of generalpurpose computer processor (CPU) 71 that can be used in an industrialsetting for controlling various chambers and sub-processors. Thecomputer may use any suitable memory 72, such as random access memory,read only memory, floppy disk drive, hard disk, or any other form ofdigital storage, local or remote. Various support circuits 73 may becoupled to the CPU for supporting the processor in a conventionalmanner. Software routines as required may be stored in the memory orexecuted by a second CPU that is remotely located.

The software routines are executed to initiate process recipes orsequences. The software routines, when executed, transform the generalpurpose computer into a specific process computer that controls thechamber operation so that a chamber process is performed. For example,software routines may be used to precisely control the activation of theelectronic control valves for the execution of process sequencesaccording to embodiments described herein. Alternatively, the softwareroutines may be performed in hardware, as an application specificintegrated circuit or other type of hardware implementation, or acombination of software and hardware.

Integrated Barrier Layer Formation

A dual-mode deposition process for forming an integrated barrier layerstructure on a substrate is described. The dual-mode deposition processis performed in a single deposition chamber and comprises a chemicalvapor deposition (CVD) step as well as a cyclical deposition step.

FIG. 4 illustrates an embodiment of the dual-mode deposition processsequence 100 detailing the various steps used for the formation of theintegrated barrier layer structure. The integrated barrier layercomprises at least a first refractory metal layer and a secondrefractory metal layer. The dual-mode deposition process may beperformed in a process chamber similar to that described above withrespect to FIGS. 2-3.

As indicated in step 102, a substrate is provided to the processchamber. The substrate may be for example, a silicon substrate havinggate regions formed thereon. Referring to step 104, a first refractorymetal layer is formed on the substrate using a first deposition mode.The first deposition mode may comprise, for example, a chemical vapordeposition process wherein a refractory metal-containing precursor isthermally decomposed.

The first refractory metal layer may comprise for example titanium (Ti),titanium nitride (TiN), tantalum (Ta), or tantalum nitride (TaN), amongothers. Suitable titanium-containing precursors for a CVD process mayinclude, for example, titanium tetrachloride (TiCl₄),tetrakis(dimethylamido)titanium (TDMAT) andtetrakis(diethylamido)titanium (TDEAT), among others. Suitabletantalum-containing precursors for a CVD process may include, forexample, pentakis(dimethylamido)tantalum (PDMAT),pentakis(ethylmethylamido)tantalum (PEMAT),tertbutylimidotris(diethylamido)tantalum (TBTDET), andpentakis(diethylamido)tantalum (PDEAT), among others.

One exemplary process of depositing a titanium nitride (TiN) layer usinga chemical vapor deposition (CVD) process comprises thermallydecomposing a titanium-containing precursor such as, for example,tetrakis(dimethylamido)titanium (TDMAT). Thetetrakis(dimethylamido)titanium (TDMAT) may be provided to radiallydispersed openings 37 (FIG. 2B) of the distribution plate 35 (FIG. 2B)in the process chamber at a flow rate between about 20 sccm to about 200sccm, preferably between about 50 sccm to about 100 sccm. A carrier gascomprising helium (He) may be provided along with thetetrakis(dimethylamido)titanium (TDMAT) at a flow rate between about 500sccm to about 2000 sccm, preferably between about 1000 sccm to about1500 sccm. The substrate may be maintained at a temperature betweenabout 200° C. to about 400° C., preferably between about 300° C. toabout 350° C., at a chamber pressure between about 5 torr to about 15torr, preferably about 10 torr.

Referring to step 106, after the first refractory metal layer is formedon the substrate using a first deposition mode, the process chamber ispurged to remove any process gases remaining therein. Suitable purgegases may include argon (Ar), helium (He) and nitrogen (N₂). Thereafter,a second refractory metal layer is formed on the first refractory metallayer using a second deposition mode, as indicated in step 108. Thesecond refractory metal layer may be formed using a cyclical depositionprocess by alternately adsorbing a refractory metal-containing precursorand a reducing gas on the substrate.

FIG. 5 illustrates an embodiment of a cyclical deposition processsequence 200 according to the present invention detailing the varioussteps used for the deposition of the second refractory metal layer. Asshown in step 202, the process chamber conditions such as, for example,the temperature and pressure are adjusted to enhance the adsorption ofthe process gases on the substrate.

In one embodiment where a constant carrier gas flow is desired, acarrier gas stream is established within the process chamber through thecenter opening 36 (FIG. 2B) in the gas distribution plate 35 (FIG. 2B),as indicated in step 204. Carrier gases may be selected so as to alsoact as a purge gas for removal of volatile reactants and/or by-productsfrom the process chamber. Carrier gases such as, for example, helium(He), argon (Ar), nitrogen (N₂) and hydrogen (H₂), and combinationsthereof, among others may be used.

Referring to step 206, after the carrier gas stream is establishedwithin the process chamber, a pulse of a refractory metal-containingprecursor is added to the carrier gas stream. The term pulse as usedherein refers to a dose of material injected into the process chamber orinto the carrier gas stream. The pulse of the refractorymetal-containing precursor lasts for a predetermined time interval.

The second refractory metal layer may comprise for example, tungsten(W), tungsten nitride (WN), or tungsten boride (W₂B), among others.Suitable tungsten-containing precursors may include, for example,tungsten hexafluoride (WF₆) and tungsten carbonyl (W(CO)₆), among others

The time interval for the pulse of the refractory metal-containingprecursor is variable depending on a number of factors such as, forexample, the volume capacity of the process chamber employed, the vacuumsystem coupled thereto and the volatility/reactivity of the reactantsused. For example, (1) a large-volume process chamber may lead to alonger time to stabilize the process conditions such as, for example,carrier purge gas flow and temperature, requiring a longer pulse time;and (2) a lower flow rate for the process gas may also lead to a longertime to stabilize the process conditions requiring a longer pulse time.In general, the process conditions are advantageously selected so that apulse of the refractory metal-containing precursor provides a sufficientamount of precursor, such that at least a monolayer of the refractorymetal-containing precursor is adsorbed on the substrate. Thereafter,excess refractory metal-containing precursor remaining in the chambermay be removed from the process chamber by the carrier gas stream incombination with the vacuum system.

In step 208, after the excess refractory metal-containing precursor hasbeen sufficiently removed from the process chamber by the carrier gasstream to prevent co-reaction or particle formation with a subsequentlyprovided process gas, a pulse of a reducing gas is added to the carriergas stream. Suitable reducing gases may include for example, silane(SiH₄), disilane (Si₂H₆), dichlorosilane (SiCl₂H₂), ammonia (NH₃),hydrazine (N₂H₄), monomethyl hydrazine (CH₃N₂H₃), dimethyl hydrazine(C₂H₆N₂H₂), t-butyl hydrazine (C₄H₉N₂H₃), phenyl hydrazine (C₆H₅N₂H₃),2,2′-azoisobutane ((CH₃)₆C₂N₂), ethylazide (C₂H₅N₃), borane (BH₃),diborane (B₂H₆), triborane (B₃H₉), tetraborane (B₄H₁₂), pentaborane(B₅H₁₅), hexaborane (B₆H₁₈), heptaborane (B₇H₂₁), octaborane (B₈H₂₄),nanoborane (B₉H₂₇) and decaborane (B₁₀H₃₀), among others.

The pulse of the reducing gas also lasts for a predetermined timeinterval. In general, the time interval for the pulse of the reducinggas should be long enough to provide a sufficient amount of the reducinggas for reaction with the refractory metal-containing precursor that isalready adsorbed on the substrate. Thereafter, excess reducing gas isflushed from the process chamber by the carrier gas stream incombination with the vacuum system.

Steps 204 through 208 comprise one embodiment of a deposition cycle forthe second refractory metal-containing layer. For such an embodiment, aconstant flow of the carrier gas is provided to the process chambermodulated by alternating periods of pulsing and non-pulsing where theperiods of pulsing alternate between the refractory metal-containingprecursor and the reducing gas along with the carrier gas stream, whilethe periods of non-pulsing include only the carrier gas stream.

The time interval for each of the pulses of the refractorymetal-containing precursor and the reducing gas may have the sameduration. That is the duration of the pulse of the refractorymetal-containing precursor may be identical to the duration of the pulseof the reducing gas. For such an embodiment, a time interval (T₁) forthe pulse of the refractory metal-containing precursor equals a timeinterval (T₂) for the pulse of the reducing gas.

Alternatively, the time interval for each of the pulses of therefractory metal-containing precursor and the reducing gas may havedifferent durations. That is the duration of the pulse of the refractorymetal-containing precursor may be shorter or longer than the duration ofthe pulse of the reducing gas. For such an embodiment, a time interval(T₁) for the pulse of the refractory metal-containing precursor isdifferent than a time interval (T₂) for the pulse of the reducing gas.

In addition, the periods of non-pulsing between each of the pulses ofthe refractory metal-containing precursor and the reducing gas may havethe same duration. That is, the duration of the period of non-pulsingbetween each pulse of the refractory metal-containing precursor and eachpulse of the reducing gas is identical. For such an embodiment, a timeinterval (T₃) of non-pulsing between the pulse of the refractorymetal-containing precursor and the pulse of the reducing gas equals atime interval (T₄) of non-pulsing between the pulse of the reducing gasand the pulse of the refractory metal-containing precursor. During thetime periods of non-pulsing only the constant carrier gas stream isprovided to the process chamber.

Alternatively, the periods of non-pulsing between each of the pulses ofthe refractory metal-containing precursor and the reducing gas may havedifferent durations. That is, the duration of the period of non-pulsingbetween each pulse of the refractory metal-containing precursor and eachpulse of the reducing gas may be shorter or longer than the duration ofthe period of non-pulsing between each pulse of the reducing gas and thepulse of the refractory metal-containing precursor. For such anembodiment, a time interval (T₃) of non-pulsing between the pulse of therefractory metal-containing precursor and the pulse of the reducing gasis different from a time interval (T₄) of non-pulsing between the pulseof the reducing gas and the pulse of the refractory metal-containingprecursor. During the time periods of non-pulsing only the constantcarrier gas stream is provided to the process chamber.

Additionally, the time intervals for each pulse of the refractorymetal-containing precursor, the reducing gas and the periods ofnon-pulsing therebetween for each deposition cycle may have the sameduration. For such an embodiment, a time interval (T₁) for the pulse ofthe refractory metal-containing precursor, a time interval (T₂) for thepulse of the reducing gas, a time interval (T₃) of non-pulsing betweenthe pulse of the refractory metal-containing precursor and the pulse ofthe reducing gas and a time interval (T₄) of non-pulsing between thepulse of the reducing gas and the pulse of the refractorymetal-containing precursor, each have the same value for each subsequentdeposition cycle. For example, in a first deposition cycle (C₁), a timeinterval (T₁) for the pulse of the refractory metal-containing precursorhas the same duration as the time interval (T₁) for the pulse of therefractory metal-containing precursor in subsequent deposition cycles(C₂ . . . C_(N)). Similarly, the duration of each pulse of the reducinggas as well as the periods of non-pulsing between the pulse of therefractory metal-containing precursor and the reducing gas in the firstdeposition cycle (C₁) is the same as the duration of each pulse of thereducing gas and the periods of non-pulsing between the pulse of therefractory metal-containing precursor and the reducing gas in subsequentdeposition cycles (C₂ . . . C_(N)), respectively.

Alternatively, the time intervals for at least one pulse of therefractory metal-containing precursor, the reducing gas and the periodsof non-pulsing therebetween for one or more of the deposition cycles ofthe second refractory metal layer may have different durations. For suchan embodiment, one or more of the time intervals (T₁) for the refractorymetal-containing precursor, the time intervals (T₂) for the reducinggas, the time intervals (T₃) of non-pulsing between the pulse of therefractory metal-containing precursor and the pulse of the reducing gasand the time interval (T₄) of non-pulsing between the pulse of thereducing gas and the pulse of the refractory metal-containing precursormay have different values for one or more subsequent deposition cyclesof the cyclical deposition process. For example, in a first depositioncycle (C₁), the time interval (T₁) for the pulse of the refractorymetal-containing precursor may be longer or shorter than the timeinterval (T₁) for the pulse of the refractory metal-containing precursorin subsequent deposition cycles (C₂ . . . C_(N)). Similarly, theduration of each pulse of the reducing gas and the periods ofnon-pulsing between the pulse of the refractory metal-containingprecursor and the reducing gas in deposition cycle (C₁) may be the sameor different than the duration of corresponding pulses of the reducinggas and the periods of non-pulsing between the pulse of the refractorymetal-containing precursor and the reducing gas in subsequent depositioncycles (C₂ . . . C_(N)), respectively.

Referring to step 210, after each deposition cycle (steps 204 through208) a total thickness of the second refractory metal will be formed onthe substrate. Depending on specific device requirements, subsequentdeposition cycles may be needed to achieve a desired thickness. As such,steps 204 through 208 are repeated until the desired thickness for thesecond refractory metal layer is achieved. Thereafter, when the desiredthickness for the second refractory metal layer is achieved the processis stopped as indicated by step 212.

In an alternate process sequence described with respect to FIG. 6, thesecond refractory metal layer deposition cycle comprises separate pulsesfor each of the refractory metal-containing precursor, the reducing gasand a purge gas. For such an embodiment, a refractory metal layerdeposition sequence 300 includes adjusting the process chamberconditions (step 302), providing a first pulse of a purge gas to theprocess chamber (step 304), providing a pulse of a refractorymetal-containing precursor to the process chamber (step 306), providinga second pulse of a purge gas to the process chamber (step 308),providing a pulse of the reducing gas to the process chamber (step 310),and then repeating steps 304 through 308, or stopping the depositionprocess (step 314) depending on whether a desired thickness for therefractory metal layer has been achieved (step 312).

The time intervals for each of the pulses of the refractorymetal-containing precursor, the reducing gas and the purge gas may havethe same or different durations as discussed above with respect to FIG.5. Alternatively, corresponding time intervals for one or more pulses ofthe refractory metal-containing precursor, the reducing gas and thepurge gas in one or more of the deposition cycles of the refractorymetal layer deposition process may have different durations.

In FIGS. 5-6, the refractory metal layer deposition cycle is depicted asbeginning with a pulse of the refractory metal-containing precursorfollowed by a pulse of the reducing gas. Alternatively, the refractorymetal layer deposition cycle may start with a pulse of the reducing gasfollowed by a pulse of the refractory metal-containing precursor.

One exemplary process of depositing a tungsten layer comprisessequentially providing pulses of tungsten hexafluoride (WF₆) and pulsesof diborane (B₂H₆). The tungsten hexafluoride (WF₆) may be provided toan appropriate flow control valve, for example, an electronic controlvalve, at a flow rate of between about 10 sccm (standard cubiccentimeters per minute) and about 400 sccm, preferably between about 20sccm and about 100 sccm, and thereafter pulsed for about 1 second orless, preferably about 0.2 seconds or less. A carrier gas comprisingargon (Ar) is provided along with the tungsten hexaflouride (WF₆) at aflow rate between about 250 sccm to about 1000 sccm, preferably betweenabout 500 sccm to about 750 sccm. The diborane (B₂H₆) may be provided toan appropriate flow control valve, for example, an electronic controlvalve, at a flow rate of between about 5 sccm and about 150 sccm,preferably between about 5 sccm and about 25 sccm, and thereafter pulsedfor about 1 second or less, preferably about 0.2 seconds or less. Acarrier gas comprising argon (Ar) is provided along with the diborane(B₂H₆) at a flow rate between about 250 sccm to about 1000 sccm,preferably between about 500 sccm to about 750 sccm. The substrate maybe maintained at a temperature between about 250° C. and about 350° C.,preferably about 300° C. at a chamber pressure between about 1 torr toabout 10 torr, preferably about 5 torr.

Another exemplary process of depositing a tungsten layer comprisessequentially providing pulses of tungsten hexaflouride (WF₆) and pulsesof silane (SiH₄). The tungsten hexafluoride (WF₆) may be provided to anappropriate flow control valve, for example, an electronic controlvalve, at a flow rate of between about 10 sccm (standard cubiccentimeters per minute) and about 400 sccm, preferably between about 20sccm and about 100 sccm, and thereafter pulsed for about 1 second orless, preferably about 0.2 seconds or less. A carrier gas comprisingargon (Ar) is provided to along with the tungsten hexaflouride (WF₆) ata flow rate between about 250 sccm to about 1000 sccm, preferablybetween about 300 sccm to about 500 sccm. The silane (SiH₄) may beprovided to an appropriate flow control valve, for example, anelectronic control valve, at a flow rate between about 10 sccm to about500 sccm, preferably between about 50 sccm to about 200 sccm, andthereafter pulsed for about 1 second or less, preferably about 0.2seconds or less. A carrier gas comprising argon (Ar) is provided alongwith the silane (SiH₄) at a flow rate between about 250 sccm to about1000 sccm, preferably between about 300 scorn to about 500 sccm. A pulseof a purge gas comprising agron (Ar) at a flow rate between about 300sccm to about 1000 sccm, preferably between about 500 sccm to about 750sccm, in pulses of about 1 second or less, preferably about 0.3 secondsor less is provided between the pulses of the tungsten hexafluoride(WF₆) and the pulses of silane (SiH₄). The substrate may be maintainedat a temperature between about 300° C. to about 400° C., preferablyabout 350° C., at a chamber pressure between about 1 torr to about 10torr.

Referring to FIG. 4, the dual-mode deposition process is depicted asforming the first refractory metal layer using a chemical vapordeposition (CVD) process followed by formation of the second refractorymetal layer using a cyclical deposition process. Alternatively, thedual-mode deposition process may start with a first refractory metallayer deposited using a cyclical deposition process followed by a secondrefractory metal layer deposited using a chemical vapor deposition (CVD)process.

Integrated Circuit Fabrication Processes

1. Copper Interconnects

FIGS. 7A-7C illustrate cross-sectional views of a substrate at differentstages of a copper interconnect fabrication sequence incorporating theintegrated barrier layer of the present invention. FIG. 7A, for example,illustrates a cross-sectional view of a substrate 400 having metalcontacts 404 and a dielectric layer 402 formed thereon. The substrate400 may comprise a semiconductor material such as, for example, silicon(Si), germanium (Ge), or gallium arsenide (GaAs). The dielectric layer402 may comprise an insulating material such as, for example, siliconoxide or silicon nitride. The metal contacts 404 may comprise forexample, copper (Cu). Apertures 404H may be defined in the dielectriclayer 402 to provide openings over the metal contacts 404. The apertures404H may be defined in the dielectric layer 402 using conventionallithography and etching techniques.

Referring to FIG. 7B, an integrated barrier layer 406 is formed in theapertures 404H defined in the dielectric layer 402. The integratedbarrier layer 406 comprises a titanium nitride (TiN) layer formed with achemical vapor deposition (CVD) process and a tungsten (W) layer formedwith a cyclical deposition process. The integrated barrier layer 406 isformed using the deposition techniques described above with respect toFIGS. 4-6. The thickness of the integrated barrier layer 406 istypically about 20 Å to about 500 Å.

Thereafter, the apertures 404H are filled with copper (Cu) metallization408 using a suitable deposition process as shown in FIG. 7C. Forexample, copper (Cu) may be deposited with a chemical vapor deposition(CVD) process using copper-containing precursors such as Cu⁺²(hfac)₂(copper hexafluoro acetylacetonate), Cu⁺²(fod)₂ (copper heptafluorodimethyl octanediene), Cu⁺¹hfac TMVS (copper hexafluoro acetylacetonatetrimethylvinylsilane), among others.

2. Gate Electrodes

FIGS. 8A-8C illustrate cross-sectional views of a substrate at differentstages of a gate electrode fabrication sequence incorporating theintegrated barrier layer of the present invention. FIG. 8A, for example,illustrates a cross-sectional view of a substrate 500 having gateregions 504 formed on the surface thereof. The gate regions 504 aresurrounded by a dielectric material 502. The substrate 500 may comprisea semiconductor material such as, for example, silicon (Si), germanium(Ge), or gallium arsenide (GaAs). The dielectric material 502 maycomprise an insulating material such as, for example, silicon oxide orsilicon nitride.

Referring to FIG. 8B, an integrated barrier layer 506 is formed on thegate regions 504. The integrated barrier layer 506 comprises a titaniumnitride (TiN) layer formed with a chemical vapor deposition (CVD)process and a tungsten (W) layer formed with a cyclical depositionprocess. The integrated barrier layer 506 is formed using the depositiontechniques described above with respect to FIGS. 4-6. The thickness ofthe integrated barrier layer 506 is typically about 20Å to about 500 Å.

Thereafter, the gate electrodes are completed by depositing gatemetallization 508 on the integrated barrier layer 506 as shown in FIG.8C. The gate metallization may comprise tungsten (W), aluminum (Al) orcopper (Cu), among others. For example, tungsten (W) may be depositedwith a chemical vapor deposition (CVD) process from the thermaldecomposition of tungsten hexafluoride (WF₆) or tungsten carbonyl(W(CO)₆); aluminum may be deposited with a chemical vapor deposition(CVD) process using dimethyl aluminum hydride (DMAH); or copper (Cu) maybe deposited with a chemical vapor deposition (CVD) process usingcopper-containing precursors such as Cu⁺²(hfac)₂ (copper hexafluoroacetylacetonate), Cu⁺²(fod)₂ (copper heptafluoro dimethyl octanediene),or Cu⁺¹hfac TMVS (copper hexafluoro acetylacetonatetrimethylvinylsilane), among others.

3. Trench Capacitors

FIGS. 9A-9D are illustrative of a metal-insulator-metal (MIM) trenchcapacitor fabrication sequence incorporating the integrated barrierlayer of the present invention. FIG. 9A, for example, illustrates across-sectional view of a substrate 655 having a dielectric materiallayer 657 formed thereon. The substrate 655 may comprise a semiconductormaterial such as, for example, silicon (Si), germanium (Ge), or galliumarsenide (GaAs). The dielectric material layer 657 may comprise aninsulator such as, for example, silicon oxide or silicon nitride. Atleast one trench 659 is defined in the dielectric material layer 657.The trench may be formed using conventional lithography and etchingtechniques.

Referring to FIG. 9B, a first integrated barrier layer 660 is formed onthe trench 659. The first integrated barrier layer 660 comprises atitanium nitride (TiN) layer formed with a chemical vapor deposition(CVD) process and a tungsten (W) layer formed with a cyclical depositionprocess. The first integrated barrier layer 660 is formed using thedeposition techniques described above with respect to FIGS. 4-6. Thethickness of the integrated barrier layer 660 is typically about 20Å toabout 500 Å.

A first metal layer 661 is formed over the first integrated barrierlayer 660. The first metal layer 661 comprises the first electrode ofthe metal-insulator-metal (MIM) trench capacitor. A suitable metal forthe first metal layer 661 includes, for example, tungsten (W). Thethickness of the first metal layer 661 is typically about 100 Å to about1000 Å.

The trench capacitor further includes an insulating layer 663 formedover the metal layer 661, as shown in FIG. 9C. The insulating layer 663preferably comprises a high dielectric constant material (dielectricconstant greater then about 10). High dielectric constant materialsadvantageously permit higher charge storage capacities for the capacitorstructures. Suitable dielectric materials may include for example,tantalum pentoxide (Ta₂O₅), silicon oxide/silicon nitride/oxynitride(ONO), aluminum oxide (Al₂O₃), barium strontium titanate (BST), bariumtitanate, lead zirconate titanate (PZT), lead lanthanium titanate,strontium titanate and strontium bismuth titanate, among others.

The thickness of the insulating layer 663 is variable depending on thedielectric constant of the material used and the geometry of the devicebeing fabricated. Typically, the insulating layer 663 has a thickness ofabout 100 Å to about 1000 Å.

A second integrated barrier layer 664 is formed on the insulating layer663. The second integrated barrier layer 664 comprises a titaniumnitride (TiN) layer formed with a chemical vapor deposition (CVD)process and a tungsten (W) layer formed with a cyclical depositionprocess. The second integrated barrier layer 664 is formed using thedeposition techniques described above with respect to FIGS. 4-6. Thethickness of the integrated barrier layer 664 is typically about 20 Å toabout 500 Å.

A second metal layer 665 is formed over the second integrated barrierlayer 664. The second metal layer 665 comprises the second electrode ofthe metal-insulator-metal (MIM) trench capacitor. A suitable metal forthe second metal layer 665 includes, for example, tungsten (W). Thethickness of the second metal layer 665 is typically about 100 Å toabout 1000 Å.

After the second metal layer 665 is formed, the metal-insulator-metal(MIM) trench capacitor is completed by filling the trench 659 with, forexample, a polysilicon layer 667, as shown in FIG. 9D. The polysiliconlayer 667 may be formed using conventional deposition techniques. Forexample, the polysilicon layer 667 may be deposited using a chemicalvapor deposition (CVD) process in which silane (SiH₄) is thermallydecomposed to form polysilicon at a temperature between about 550° C.and 700° C.

4. Crown Capacitors

FIGS. 10A-10B illustrate cross-sectional views of a substrate atdifferent stages of a crown capacitor fabrication sequence incorporatingthe integrated barrier layer of the present invention. The term crowncapacitor as used herein refers to a capacitor structure having athree-dimensional shape formed above the surface of the substrate. Thethree-dimensional shape increases the capacitance of the device byincreasing the surface area thereof.

FIG. 10A, for example, illustrates a cross-sectional view of a substrate712 having a dielectric layer 714 formed thereon. The substrate 712 maycomprise a semiconductor material such as, for example, silicon (Si),germanium (Ge), or gallium arsenide (GaAs). The dielectric 714 maycomprise an oxide such as, for example, a silicon oxide. The dielectriclayer 714 has at least one aperture 716 formed therein.

A first polysilicon layer 718 is formed over the dielectric layer 714and the at least one aperture 716. The first polysilicon layer 718 maybe doped with a suitable dopant such as, for example, arsenic (As),antimony (Sb), phosphorous (P) and boron (B), among others.

A hemispherical silicon grain layer (HSG) 720 or a rough polysiliconlayer may optionally be formed over the first polysilicon layer 718 toincrease the surface area thereof. The hemispherical silicon grain layer720 may be formed, for example, by depositing an amorphous silicon layerand than annealing it to form a rough surface thereon. The hemisphericalsilicon grain layer 720 may optionally by doped.

The first polysilicon layer 718 and the hemispherical silicon grainlayer (HSG) 720 are patterned and etched to form a crown structure 730.Both the first polysilicon layer 718 and the hemispherical silicon grainlayer (HSG) act as a first electrode for the crown capacitor.

The crown capacitor further includes an insulating layer 732 formed overthe hemispherical silicon grain layer 718 of the crown structure 730.The insulating layer 732 preferably comprises a high dielectric constantmaterial (dielectric constant greater then about 10). High dielectricconstant materials advantageously permit higher charge storagecapacities for the capacitor structures. Suitable dielectric materialsmay include for example, tantalum pentoxide (Ta₂O₅), siliconoxide/silicon nitride/oxynitride (ONO), aluminum oxide (Al₂O₃), bariumstrontium titanate (BST), barium titanate, lead zirconate titanate(PZT), lead lanthanium titanate, strontium titanate and strontiumbismuth titanate, among others.

Referring to FIG. 10B, an integrated barrier layer 734 is formed on theinsulating layer 732. The integrated barrier layer 734 comprises atitanium nitride (TiN) layer formed with a chemical vapor deposition(CVD) process and a tungsten (W) layer formed with a cyclical depositionprocess. The integrated barrier layer 734 is formed using the depositiontechniques described above with respect to FIGS. 4-6. The thickness ofthe integrated barrier layer 734 is typically about 20 Å to about 500 Å.

A metal layer 742 is formed over the integrated barrier layer 734. Themetal layer 742 comprises the second electrode of the crown capacitor. Asuitable metal for the metal layer 742 includes, for example, tungsten(W). The thickness of the metal layer 742 is typically about 100 Å toabout 1000 Å.

After the metal layer 742 is formed, the crown capacitor is completed bydepositing, for example, a second polysilicon layer 752 thereover, asshown in FIG. 10B. The second polysilicon layer 752 may be formed usingconventional deposition techniques. For example, the second polysiliconlayer 752 may be deposited using a chemical vapor deposition (CVD)process in which silane (SiH₄) is thermally decomposed to formpolysilicon at a temperature between about 550° C. and 700° C.

While the foregoing is directed to the preferred embodiment of thepresent invention, other and further embodiments of the invention may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

1. A method for forming an integrated barrier material on a substrate,comprising: positioning a substrate within a process chamber; forming anintegrated barrier layer on the substrate by a cyclical depositionprocess and a chemical vapor deposition process, wherein the integratedbarrier layer comprises metallic tungsten, tungsten nitride, or tungstenboride; and depositing a tungsten metallization layer over theintegrated barrier layer during a thermal chemical vapor depositionprocess.
 2. The method of claim 1, wherein the process chamber comprisesa distribution plate configured for the cyclical deposition process andthe chemical vapor deposition process.
 3. The method of claim 2, whereinthe distribution plate comprises a first distribution zone fluidlyisolated from a second distribution zone.
 4. The method of claim 3,wherein the first distribution zone comprises a center opening and thesecond distribution zone comprises a plurality of openings radiallydispersed around the center opening.
 5. The method of claim 1, whereinthe integrated barrier layer comprises tungsten nitride deposited by thecyclical deposition process.
 6. The method of claim 5, wherein thesubstrate is sequentially exposed to tungsten hexafluoride and ammoniaduring the cyclical deposition process.
 7. The method of claim 1,wherein the integrated barrier layer comprises tungsten nitridedeposited by the chemical vapor deposition process.
 8. The method ofclaim 7, wherein the substrate is exposed to tungsten hexafluoride andammonia during the chemical vapor deposition process.
 9. The method ofclaim 1, wherein the integrated barrier layer comprises metallictungsten deposited by the cyclical deposition process.
 10. The method ofclaim 9, wherein the substrate is sequentially exposed to tungstenhexafluoride and a reducing gas during the cyclical deposition process.11. The method of claim 10, wherein the reducing gas comprises areducing agent selected from the group consisting of silane, disilane,and diborane.
 12. The method of claim 1, wherein the integrated barrierlayer comprises metallic tungsten deposited by the chemical vapordeposition process.
 13. The method of claim 12, wherein the substrate isexposed to tungsten hexafluoride and a reducing gas during the chemicalvapor deposition process.
 14. The method of claim 13, wherein thereducing gas comprises a reducing agent selected from the groupconsisting of silane, disilane, and diborane.
 15. An apparatus forprocessing a substrate, comprising: a process chamber; a dual-mode gasdistribution plate disposed within the process chamber, wherein thedual-mode gas distribution plate is configured to dispense process gasesfor a chemical vapor deposition process and a cyclical depositionprocess; a nitrogen precursor source in fluid communication with a firstgas distribution zone of the plate configured to perform cyclicaldeposition process; and a tungsten precursor source in fluid with asecond gas distribution zone of the plate configured to perform chemicalvapor deposition process.
 16. The apparatus of claim 15, wherein thefirst gas distribution zone and the second gas distribution zone of thedual-mode gas distribution plate are isolated one from the other by oneor more seals.
 17. The apparatus of claim 16, wherein the first gasdistribution zone comprises a center opening through which process gasesare provided to the process chamber.
 18. The apparatus of claim 16,wherein the second gas distribution zone comprises a plurality ofopening radically disposed around the center opening of the first gasdistribution zone.
 19. An apparatus for processing a substrate,comprising: a process chamber; a dual-mode gas distribution platedisposed within the process chamber, wherein the dual-mode gasdistribution plate is configured to dispense process gases for achemical vapor deposition process and a cyclical deposition process,wherein the dual-mode gas distribution plate comprises a first gasdistribution zone and a second gas distribution zone, and wherein thesecond gas distribution zone surrounds the first gas distribution zone;a nitrogen precursor source in fluid communication with the firstdistribution zone; and a tungsten precursor source in fluidcommunication with the second distribution zone, wherein the nitrogenprecursor source is in fluid communication with a electronic controlvalve configured for the cyclical deposition process and the tungstenprecursor source is in fluid communication with a mass flow controllerconfigured for the chemical vapor deposition process.
 20. The apparatusof claim 19, wherein the process gases supplied from first gasdistribution zone is configured to deposit a first metal layer on asubstrate and the process gases supplied from the second distributionzone is configured to deposit a second metal layer on the substrate.